Document U.S. Pat. No. 5,135,539 has already disclosed a heart prosthesis which is implantable in the pericardial cavity of a patient and which is able to replace the natural left and right ventricles of said patient after their removal. This heart prosthesis comprises a rigid body in which artificial left and right ventricles are arranged, each of these artificial ventricles comprising a flexible membrane:                which is able to beat under the action of a hydraulic fluid, and        which is arranged in a cavity divided in a leaktight manner by said membrane into two chambers, one of which is intended for the circulation of the blood, and the other of which is filled with said hydraulic fluid.        
Furthermore, the hydraulic fluid chamber of each of said artificial ventricles is connected to an individual hydraulic actuator, which itself communicates with a leaktight pouch surrounding the prosthesis and containing said hydraulic fluid. The blood chamber of the artificial left ventricle comprises an orifice of connection to the natural left auricle and means of connection to the aorta, while the blood chamber of the artificial right ventricle comprises an orifice of connection to the natural right auricle and means of connection to the pulmonary artery, the axes of said orifices of connection to the natural auricles being co-planar, and said artificial ventricles having, parallel to the plane of said axes of said orifices, directions arranged in a V-shape, such that said ventricles approach each other as they move away from said orifices of connection to the natural auricles.
In the embodiment in document U.S. Pat. No. 5,135,539, the artificial ventricles of said heart prosthesis are arranged in a strictly symmetrical fashion with respect to a median plane, with their opposing individual hydraulic actuators protruding laterally from said rigid body. This has the result that the overall size of said prosthesis is not optimal and that difficulties may arise during implantation in the thoracic and pericardial cavity of many patients.